The U.S. Environmental Protection Agency (EPA) has developed effluent limitation guidelines (ELGs) as national regulatory standards to control wastewater discharges of pollutants into surface waters and publicly owned treatment works (POTWs). To date, the EPA has issued ELGs for 59 industrial categories. The wastewater treatment plant effluent standards apply to about 40,000 facilities that discharge directly into surface waters and 129,000 facilities that discharge to POTWs.

Notably, ELGs are not based on environmental risk or the impact on receiving waters. Instead, the EPA bases them on the performance and cost of demonstrated wastewater control and treatment technologies for specific regulated pollutants.

This blog post explores how the EPA develops these standards and how partnering with a team of wastewater engineers can help meet compliance requirements. 

An overview of wastewater treatment plant effluent standards

The U.S. EPA reviews, revises and updates effluent limitation guidelines annually, as required by the Effluent Guidelines Program plan. The plan identifies industries selected for regulatory revisions and new industries identified for regulation.

The most recent update for effluent guidelines, Effluent Guidelines Program Plan 15, was published in January 2023. It focused on the EPA's 2021 PFAS strategic roadmap to revise the effluent limitation guidelines for PFAS in wastewater discharges. The preliminary effluent guidelines program plan 16 (Preliminary plan 16) has been announced, underlining the agency's intent to conduct several new detailed studies of industrial categories.

Types of pollutants in effluent

The Clean Water Act categorizes pollutants in effluent into three main types:

• Conventional pollutants. These include biochemical oxygen demand (BOD), total suspended solids (TSS), fecal coliform, pH and any additional pollutants (oil and grease) that are defined as conventional pollutants.

• Toxic pollutants. The EPA has identified 65 toxic pollutants and classified 126 specific substances as priority toxic pollutants.

• Nonconventional pollutants. All other pollutants not classified as conventional or toxic fall under this category.

The following are the several levels of control for regulated pollutants as defined under the Clean Water Act (CWA). At these levels of control, technology-based numeric limitations for specific pollutants are set. 

EPA’s levels of control for pollutants in effluent

Best Practicable Control Technology available (BPT): The EPA considers factors such as facility age, cost of implementation and engineering feasibility when setting these standards.

Best Conventional Pollutant Control Technology (BCT): BCT standards address conventional pollutants from industrial point sources.

Best Available Technology economically achievable (BAT): BAT represents the best available economically achievable performance of industrial plants.

New Source Performance Standards (NSPS): These national, uniform, technology-based standards apply to direct dischargers to POTWs from specific industrial categories.

Pretreatment Standards for Existing Sources (PSES): These are national, uniform, technology-based standards that apply to indirect dischargers. PSES helps limit the discharge of pollutants that pass through, interfere with or are incompatible with POTWs.

Best Management Practices (BMPs): BMPs are defined as a permit condition used in place of, or along with effluent limitations, to limit or control the discharge of pollutants.

The following table highlights planning and implementing wastewater treatment plant effluent standards.

Planning and implementation of wastewater treatment plant effluent standards

Planning process: The ELG planning process supports the EPA’s goal of restoring and maintaining the integrity of U.S. surface waters. The EPA considers four key factors when revising ELGs: Performance of demonstrated wastewater treatment technologies. Associated costs, process changes and pollution prevention alternatives.  Types and quantities of pollutants discharged by an industry.  Opportunities for technological innovation and improved efficiency.

Implementation: The effluent guidelines and pretreatment standards are implemented through the National Pollutant Discharge Elimination System permit program and the National Pretreatment Program, respectively. Direct dischargers are regulated by permits that specify limits using BAT, BCT, BPT and NSPS. Indirect dischargers are regulated through standards issued based on PSNS and PSES.

Adhering to the wastewater treatment plant effluent standards is critical for industries. Partnering with an expert can help determine the most effective and economical technology to limit pollutants in the effluent.

How Fehr Graham can help communities comply with wastewater treatment plant effluent standards​

​At Fehr Graham, we are committed to strengthening wastewater infrastructure across communities. Our team of licensed and certified engineers devise custom, industry-specific treatment solutions to help your business meet effluent standards.

Matthew Johnson is a Professional Engineer and Structural Engineer with comprehensive experience leading water and wastewater infrastructure projects. As one of the firm’s owners, he works with clients to find solutions that best meet their needs. Matthew’s a firm believer that one size (or solution) does not fit all, so he listens to clients to help them get the outcome that’s best for their situation. He has a knack for explaining complex situations in easy-to-understand ways so clients can make the best decisions. He can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it..